The invention relates to a sieve apparatus, a supplemental device for a sieve apparatus, as well as a sieve process.
The effectiveness of sieve apparatuses depends upon the movement of the fine-grained portion in the sieve product. It would be ideal if a sieve product feeding gave each undersized particle the possibility of meeting a sieve opening and falling through.
In principle, oscillating sieves are already in use for this reason if no other, an example being linear acting oscillating sieves. By using vibrating or oscillating sieves of this type, the screening or classification of the sieve product, i.e. the sieve process itself, is embodied in a more effective and efficient manner.
British Patent GB-A 1 462 038, which defines the generic type of the invention discloses a vapor extraction apparatus which includes a sieve apparatus disclosed in a closed housing. The mixture of dust and vapor is supplied to this so-called extraction chamber via an inlet flap and is moistened by means of a sprayer device. Via a shaft disposed crosswise to the feed direction, paddles are set into rotation in order to reinforce the flow motion of the sieve product.
German Patent Disclosure DE-B 12 66 115 describes an apparatus for sieving material that contains clumps and lumps. The sieve material is once again fed via a funnel to an inclined sieve. A device for loosening the clumps and lumps is provided above the sieve face in stationary fashion; it includes a substantially vertically oriented shaft, which is drivable via a motor and from which a plurality of protruding bars extend that are seated on it, distributed in the circumferential direction. The pivot axis of the bars is disposed vertically to or inclined relative to the screen lining. In other words, the circular motion of the bars can take place in a circular plane that is parallel to or inclined relative to the sieve lining. These rotating bars are intended to loosen up the mixed scrap appropriately, so as to improve and reinforce the sieveing process.
From the WPI data base, section Ch, week 7642, a sieve apparatus is known which includes two worm extruders extending to a vertically disposed pivot shaft disposed between them. Rotating around the vertical axis are the worm extruders, which advance the sieve material in the radial direction. This involves purely a device for feeding and advancing the sieve product to the edge of the sieve.
A cleaning device for a sieve has been disclosed by British Patent GB-A 1 069 063, It includes metal sheets, formed like an inverted V, which rest with their open side on the top of a sieve in the form of a perforated plate and can be displaced along the sieve by means of chains that are laid on the underside of the V- shaped sheets. This "cleaning effect" is intended to encounter plugging up or stoppage of the sieve holes. In the forward motion of these V-shaped sieve sheets, the sieve product is raised on one ramplike side and deposited again in the direction of the sieve face on the other ramplike side of the sheet.